Text Case Converter
Paste text and convert it between every common case style — sentence and title case for writing, camel, snake, kebab and constant case for code. Title case follows proper style rules rather than simply capitalising every word.
- Free, no sign-up
- Runs in your browser
- Nothing uploaded
- Updated Sep 2026
For writing
For code
At a glance
- Writing styles
- Sentence case, Title Case, UPPERCASE, lowercase
- Code styles
- camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE
- Title case
- Small words stay lowercase unless first or last
- Preserves
- Known acronyms such as API, URL, JSON, HTML
- Processing
- Entirely client-side
- Cost
- Free, no account
Sentence case, title case, and which to use
These two get confused constantly, and the difference matters for headings.
Sentence case capitalises only the first word and any proper nouns: How to convert JSON to YAML. Title case capitalises the principal words and leaves short function words lowercase: How to Convert JSON to YAML.
Naive title case — capitalising every word — produces How To Convert JSON To YAML, which is wrong in every major style guide. The rule is that articles (a, an, the), coordinating conjunctions (and, but, or) and short prepositions (in, on, to, of) stay lowercase — unless they are the first or last word, where they are always capitalised. This tool implements that rule.
Which to choose is a house-style decision. Sentence case has become the dominant choice in software and product writing because it reads more naturally and is far harder to get wrong. Title case remains standard in journalism and academic publishing. The important thing is picking one and applying it consistently — mixed heading styles on a site look careless in a way readers notice without being able to say why.
The programming cases and where each belongs
| Style | Example | Conventional use |
|---|---|---|
| camelCase | userAccountId | Variables and functions in JavaScript, Java, Swift |
| PascalCase | UserAccountId | Classes and types in most languages; C# methods |
| snake_case | user_account_id | Python and Ruby variables; SQL columns |
| kebab-case | user-account-id | URLs, CSS classes, HTML attributes, CLI flags |
| CONSTANT_CASE | USER_ACCOUNT_ID | Constants and environment variables everywhere |
Two of these have consequences beyond taste. kebab-case in URLs matters because Google reads hyphens as word separators and underscores as joiners — see the slug generator for more on that. And kebab-case is required in CSS and HTML: an identifier with an underscore works, but every convention and linter expects hyphens.
The conversion between styles is mechanical once word boundaries are identified, which is
the part that is easy to get wrong. This converter splits on existing separators, on
lowercase-to-uppercase transitions, and on the boundary inside acronym runs — so
parseHTMLDocument correctly becomes parse_html_document rather than
parse_h_t_m_l_document.
Acronyms, and why naive conversion mangles them
The common failure in case conversion is what happens to acronyms. json api url
title-cased naively becomes Json Api Url, which looks amateurish in technical
writing. Converting getHTTPResponse to snake case naively produces
get_h_t_t_p_response.
This converter keeps a list of common technical acronyms — API, URL, JSON, XML, HTML, CSS,
HTTP, HTTPS, SQL, PDF, CSV, YAML, UI, UX, ID, AI, LLM, SEO and others — and preserves their
capitalisation through title and sentence case. For code styles, consecutive capitals are
treated as a single word unit, which is what produces get_http_response.
It is not exhaustive, and it cannot be: your product names, internal abbreviations and domain-specific terms are not in any general list. For those, convert and then fix the handful of terms by hand — usually a two-second edit on output that is otherwise correct.
How to use the Case Converter
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Paste your text
Anything from a single heading to a whole document. Conversion happens as you type.
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Pick a case style
The writing styles are grouped separately from the programming ones. Each shows a live preview.
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Check acronyms and proper nouns
Common technical acronyms are preserved automatically. Product names and internal abbreviations will need a manual fix.
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Copy the result
Copy it straight out, or download longer text as a file.
Frequently asked questions
What is the difference between sentence case and title case?
Sentence case capitalises only the first word and proper nouns — How to convert JSON to YAML. Title case capitalises the principal words while leaving short articles, conjunctions and prepositions lowercase — How to Convert JSON to YAML. Capitalising every word is neither, and is wrong in every major style guide.
Which words stay lowercase in title case?
Articles (a, an, the), coordinating conjunctions (and, but, or, nor, for, yet, so) and short prepositions (in, on, at, to, of, by, up). The exception is that the first and last word are always capitalised regardless.
When should I use camelCase versus snake_case?
Follow the convention of the language you are writing in. JavaScript, Java and Swift use camelCase for variables; Python, Ruby and SQL use snake_case. Consistency within a codebase matters far more than any argument about which is better.
Why does the converter keep some words capitalised?
It preserves common technical acronyms — API, URL, JSON, HTML and similar — because lowercasing them to Json or Api reads as an error in technical writing. Your own product names and internal abbreviations are not in the list and will need fixing by hand.
Does changing case affect SEO?
Not directly in headings — Google reads the words, not the capitalisation. It does matter in URLs, where paths are case-sensitive on most servers, so /Page and /page are two different URLs and can create duplicate content. Keep URLs lowercase always.
Can it handle accented and non-English text?
Yes for case conversion — accented characters uppercase and lowercase correctly. Title-case small-word rules are English-specific, so they will not match the conventions of other languages, which vary considerably.